The present invention relates to truck tire treads and tires for steer axles.
The use of treads specifically designed for the steer axle of truck tires is well known in the art. It is also known, however, that improvements were desired.
One problem is related to stones. It is known in the art for stones to become trapped or held within the grooves of the tread. Such stones may damage the groove bottoms and the belt-package that lies beneath the tread. Such damage caused by stones is known as "stone drilling."
Another problem relates to irregular wear in the shoulder ribs of steer tires. Such irregular shoulder wear is known to produce peaking on the inside edge of the shoulder rib and drop off on the outside edge of the shoulder rib.
The applicants have also noticed that, even though the molds used to produce steer tires are typically made with an equal width for shoulder and centerline grooves, the tire when in use may produce a footprint having shoulder grooves that are opened-up or greater in width than the centerline grooves. This opening of the shoulder grooves relative to the centerline grooves results in a lower local net-to-gross ratio. Since the same load must be carried, the footprint length increases locally yielding peaking around the shoulder grooves.
The present invention provides circumferential grooves that are wide enough to permit a tread gauge to be used to measure the full intended non-skid depth, yet are narrow enough to prevent any stones of significant size to enter the grooves. The present invention also minimizes irregular shoulder wear by using a single radius plus "mixed" shoulder off-set design.